1917 ENTOMOLOGICAL SOCIETY. 91 



unt>atisf;utory as a control measure. Fortunately that same year I was studying 

 the very closely related two species of Cherry Fruit-flies, and found in the course 

 of my work ])roof that these moved around freely from tree to tree, though we 

 should not have suspected it to watch them. This discovery along with the excellent 

 results obtained .against the Cherry Fruit-flies by the use of arsenate of lead and 

 molasses, led us to hope that l)y spraying a whole orchard at a time, or at least very 

 large blocks of trees, the same good results from the poison on the Apple Maggot 

 might be obtained as had been so easily obtained against the Cherry Fruit-flies, 

 Acting on this hope we conducted a series of spraying experiments with sweetened 

 arsenate of lead in 1914, 1915 and 1916, and as a result of these experiments both 

 of us were thoroughly convinced that arsenate of lead and molasses was a simple 

 and satisfactory means of control. We did not try, except in cage experiments, 

 arsenate of lead, or any other poison alone, simply because we found it difficult to 

 discover a sufficient number of orchards in which to make satisfactory and separate 

 tests of more than the one remedy. We plan next year to make such tests, and 

 also some others that we have been working on this year in a small way in cages, 

 and that seem to promise well. 



As to the length of time it takes arsenate of lead to kill the adult, I cannot 

 recall the results ^Messrs. TJoss and Good obtained, but this year I conducted a series 

 of cage experiments begun shortly after the flies began to emerge, and continued 

 until they disappeared from the orchard. These showed that flies caught in the 

 orchard without injuring them and put into cages with poisoned and unpoisoned 

 leaves and fruit in the same cage and watered daily, died on an average in less than 

 three days, whereas the check flies lived a much longer time. Moreover, there is 

 good reason to believe that even though an orchard is not sprayed until a number of 

 flies are ready to lay eggs, the poison acts in such a way as to stop eg^ laying almost 

 at once after it is eaten In' the fly, even though she herself may live a few days 

 longer before death ensues. 



As to the sweetened poison attracting flies from some distance, I have never 

 been able to see the least proof that this was true either of the Cherry Fruit-flies 

 or of the Apple ^Maggot. They merely eat it if it happens to be on the leaf or fruit 

 where they are feeding; they do not go in search of it. 



EXPERIMENTS ON THE CONTKOL OF LOCUSTS WITH COCCO- 

 BACILLUS ACRIDIORUM D'HERELLE. 



E. Melville DuPorte and J. Yanderleck, Macdonald College, Que. 



Since 1910, when d'Herelle isolated from diseased locusts in Mexico a bacterial 

 organism causing an epidemic disease in these insects, efforts have been made in 

 various parts of the world to utilize this organism in the destruction of locusts. 

 D'Herelle himself in the year following his investigations in Mexico, conducted 

 experiments in the Province of Santa Fe in Argentina, and reported remarkable 

 success. 



Sergent and riTeritier, working in Algeria in 191:1, did not have an unquali- 

 fied success in their attempts to disseminate this disease, for while they were able 

 to collect dead locusts by hundreds in the areas which they had infected, they found 

 that the size of the swarms was not appreciably diminished. They attributed their 

 failure to three contingencies. Either the infection did not spread through the 

 majority of the migrating swarms, or many of the locusts possessed a natural im- 

 munity, or else they easily acquired an active immunity against the organism. 



